Top reasons why MPLS has been widely successful

The IETF Thursday threw a birthday party for one of its most successful standards: Multi-Protocol Label Switching.

The Internet’s leading standards body hosted a panel discussion outlining the reasons why the 12-year-old protocol has been so widely deployed and such a big moneymaker for carriers.

“MPLS is one of our wildly successful protocol suites,” said Loa Andersson, co-chair of the IETF’s MPLS Working Group and the principal networking architect at the Swedish Research Institute, Acreo AB. Andersson served as moderator for the panel, which was hosted by the Internet Architecture Board, a sister organization to the IETF.

“The major applications that are making money on the Internet are on MPLS,” said George Swallow, a Distinguished Engineer at Cisco and the MPLS Working Group Co-Chair.

With MPLS, the IETF integrated the label-switching capabilities of Asynchronous Transfer Mode with the packet orientation of the Internet Protocol. The IETF formed its MPLS Working Group in January 1997, and protocol specifications began trickling out a few years later.

In reviewing the history of the MPLS, the panelists outlined several reasons why MPLS has been so successful. These reasons are a roadmap for anyone trying to develop a successful Internet technology.

Here are the seven reasons why MPLS has proven so popular:

1. MPLS embraced IP

In the early 1990s, the telecom industry was pinning all of its hopes on ATM as the network backbone technology of the future. But in 1995, the Internet exploded, and carriers had to quickly refocus their efforts in a different direction. By 1996, IETF researchers were looking for ways to make circuit-oriented ATM technology run over IP. ATM proponents jumped aboard the MPLS bandwagon in 1997, when the IETF formed its MPLS Working Group. Swallow says the MPLS team was wise to embrace—rather than fight—IP.

2. MPLS is flexible

MPLS has built-in flexibility in several ways, Swallow says. The control plane and the data plane are separate, which allows for many control planes and many forwarding controls. That independence creates a lot of flexibility, Swallow says. Loose semantics allow for flexible control, as does the fact that MPLS supports a label stack of undetermined size. MPLS designers also figured out a simple but flexible way to handle unicast forwarding.

3. MPLS is protocol neutral

MPLS was designed to work in a multiple protocol environment. That allowed MPLS to work with ATM, Frame Relay, Sonet or Ethernet at the core. As backbone network technologies evolved, MPLS was able to evolve, too. MPLS also played a key role in supporting both legacy network technologies and the latest IP-based technology. Today, MPLS is being used to support metro-Ethernet services, mobile communications back-haul communications and video distribution.

4. MPLS is pragmatic

Juniper Fellow Kireeti Kompella says MPLS is “a study in pragmatism.” He says the architecture created only two new protocols – Label Distribution Protocol (LDP) and Link Management Protocol (LMP) – and that everything else incorporated existing protocols. Another feature of MPLS that was pragmatic is that many MPLS specs came in competing pairs, and these pairs forced each other to improve. Although it required duplicative work for vendors, Kompella says this strategy “did a lot for the winning spec.”

5. MPLS is adaptable

MPLS has been able to evolve over time to support new applications and services, including Layer 2 and Layer 3 VPNs, Ethernet services and traffic engineering. Tom Bechly, a network engineer with Verizon, says MPLS has been successful for service providers because it allowed them to grow networks quickly, add new services and reduce costs. Kompella says the MPLS protocol spec has “lots of wiggle room” which gave the MPLS Working Group room for extensibility. This was key because the reasons why carriers deployed MPLS changed between when the protocol was envisioned and when it was deployed, Kompella says.

6. MPLS supports metrics

The best network technologies have a measurable return on investment. Carriers love the fact that MPLS allows them to gather a wide range of statistics that they can use for network traffic trend analysis and planning. With MPLS, it’s possible to measure traffic volume, latency and delay between two routers. Carriers also can measure traffic between hubs, metros and regions. Bechly says the ability to gather these statistics using MPLS is more important than path control.

7. MPLS scales

Successful Internet technologies need to be able to scale quickly, and MPLS was able to do that. Verizon uses MPLS for several global networks including its public and private IP networks as well as the vBNS network that supports the U.S. research community. Verizon’s Public IP network, for example, spans 410 points of presence on six continents and spans more than 150 countries. Bechly says these massive networks showed that “MPLS did work, and that it worked on a significant scale.”